The present invention relates generally to automotive and industrial power transmission where a variation in the speed supplied by a power source is required. The invention further relates to industrial brakes as it may be used to control or reduce the speed of any rotating force without friction.
Various designs of variable speed transmissions (VSTs), manual and automatic transmissions, speed reducers, clutches, brakes, and torque converters have been used to supply a desired output speed to a mechanical device, such as an output shaft used to rotate a drive axle. However, such designs use friction devices in order to vary the output speed. Friction is purposely used in order to slow the output speed.
Such designs which purposely use friction for speed reduction are wasteful of the energy supplied to the prime mover such as motor or engine. Extra gasoline or other fuel or electrical energy will be required if one is using friction for speed reduction. This drives up costs of operation and lowers the energy efficiency in any such system using the friction devices.
Often transmissions are limited to certain discrete ratios of input speed to output speed. Such discrete speed ratios prevent one from running the prime mover at its most efficient speed and simultaneously having the flexibility to adjust the speed of an output load (such as a drive axle) over a continuous range of speeds.
The following patents are noted as showing various types of transmissions:
______________________________________ Inventor U.S. Pat. No. Issue Date ______________________________________ McGarraugh 4,867,012 Sep. 19, 1989 Bay 5,474,504 Dec. 12, 1995 Simkins 5,516,132 May 14, 1996 Lardy 5,540,632 Jul. 30, 1996 ______________________________________
Although the above and other designs have been somewhat useful, they are often subject to one or more of several disadvantages.
The speed ratios between input and output may be limited to specific values.
The range of possible output speeds may be unduly limited. (In other words, even where output speed can be continuously varied, the range over which it can be varied is limited more than desirable.)
Often such devices generate excessive friction or at least a certain amount of friction generated purposefully in order to operate.
Prior designs often generate excessive noise under certain operating conditions.
Shifting between different speed ratios in prior designs often results in a jerking of the mechanism (and vehicle if used to power a vehicle).